Musicians and vocalists have a wide range of audio signal processing systems available to them during recording sessions. One system widely used in professional recording studios is a workstation with Digidesign's ProTools audio mixer software. These workstations include a wide variety of software sound effects libraries, sampling sequences and other so-called “plug-ins” that can be used to manipulate the audio instrument or vocal source. They also include virtual instrument and vocal libraries that can be “played” and recorded in response to signals (e.g., Musical Instrument Digital Interface (MIDI) trigger signals) inputted into the workstation. Using a “celebrity” guitarist sound effect library, for example, the workstation can manipulate any inputted guitar signal in such a manner as to have the signature sounds of that celebrity guitarist. The sound of vocalists can be enhanced by manipulating dynamics, correcting pitch or by injecting reverberation or digital delay to mask undesirable vocal characteristics, or to enhance appealing ones. Instrument libraries include the notes and other sound features of virtually all commonly used instruments. Using any MIDI-compatible source such as a keyboard, drum pad or stringed instrument, a musician can “play” and record music with any of these instruments. Systems of these types are, however, very complex and require extensive training to be used effectively. They are also relatively expensive. For these reasons they are not suitable for use during live musical and/or vocal performances.
Audio sound manipulation systems used for live performances are also available, although these systems generally offer relatively limited functionality. Guitarists, for example, commonly use effects pedals or stomp boxes to manipulate the sound of their guitars during live performances. Stomp boxes are special-purpose audio processors connected between the guitar and amplifier that manipulate the clean guitar signal in predetermined manners. Distortion, fuzz, reverberation, and wah-wah are examples of the effects that can be added to the signal produced by the guitar itself before it is amplified and played to the listeners through speakers during a performance. A number of different stomp boxes can be chained together to provide the guitarist the ability to effect the sound in many different ways.
An effects processor that has the capability of providing greater varieties of plug-ins for live performances is the Plugzilla audio processor available from Manifold Labs. Audio sources interface to the Plugzilla processor through a conventional mixer. The functionality of this processor is, however, relatively limited, and it can be difficult to operate.
There remains a need for improved audio signal processing systems suitable for use with live performances. Such a system should be capable of providing a large variety of sound manipulation functions. The system should be relatively easy to use and operate. To be commercially viable, it should also be relatively inexpensive.